1. Field of the Invention
This invention is utilized in the technical field of sweepers for cleaning up a floor. More particularly, the invention relates to a floor burnisher or polisher provided with a pad which is rotated at a high speed to polish a floor when the floor burnisher or polisher is moved by hand or by motor.
2. Brief Description of the Prior Art
In order to clean up a floor, there is generally required a floor scrubbing operation for scrubbing a floor with a scrubbing pad after a liquid detergent is spread over the floor and wiping off dirty water produced by the scrubbing and a floor burnishing or polishing work for buffing and polishing up a floor after a wax is applied onto the floor which was scrubbed. The first-mentioned floor scrubbing operation can automatically be performed by a floor scrubber including a scrubbing pad and a squeegee for absorbing dirty scrubbing water, whereas the second-mentioned floor burnishing or polishing work can be automatically performed using a floor burnisher or a floor polisher including a polishing pad which is able to rotate at a high speed.
In the conventional floor burnisher or polisher, the ground pressure of the pad against a floor has an important significance because the polishing pad is rotated at a high speed such as about 2,000 rpm. That is, in case the ground pressure of the pad against the floor is too weak, the force for polishing the floor becomes insufficient. On the contrary, in case the ground pressure is too strong, the outer surface of the floor material is heated by frictional heat and as a result, the wax applied onto the outer surface thereof is changed to yellow. And, in some extreme cases, the floor material is damaged. However, since the conventional floor burnisher or polisher is designed such that the pad thereof is rotated at a constant speed and thus at a predetermined ground pressure, it cannot adequately follow changes in a ground pressure due to various causes such as changes in the state of a floor, wear of the pad surface and the like. Therefore, the above-mentioned problems due to too weak or too strong ground pressure always occur.
Furthermore, if the pad is kept rotating when travel of the floor burnisher or polisher is stopped, the floor will be heated by friction heat resulting in peeling of wax applied onto the floor or damage to the floor material. Therefore, when the conventional floor burnisher or polisher is stopped, the pad must immediately be stopped rotating by turning off the switch of the pad motor. However, because the pad is rotated at such a high speed of about 2,000 rpm, as previously described, even if the motor is immediately stopped, the pad is still kept rotating for some time due to the force of inertia. As a result, the floor is excessively heated or damaged by the undesirable extrarotation of the pad as mentioned.
The present invention has been accomplished in order to overcome the problems inherent in the prior art.